Work out your digital carbon footprint using the CO2.js open-source tool

The CO2.js open-source tool

Developers working on software, websites and apps can use CO2.js to estimate the carbon emissions associated with internet traffic. The tool also offers access to high-quality data on the net intensity of different countries and regions around the world. So developers get a better picture of the environmental and climate impact of their digital products. "The Green Web Foundation's goal is a fossil-fuel-free internet by 2030," explains Hannah. "That will require all forms of energy consumption associated with internet use to be based on renewable sources. Our mission is a huge global challenge. Practical, open-source tools are vital to our ability to meet that challenge, because the digital supply chain is extremely complex. When you use an app or visit a website, for example, you're fetching data from lots of different sources, including services, data centres and cloud repositories. And all of them are using different amounts of energy of different types. Mapping that energy consumption is a huge job. All the more so because the data required is often inaccessible. So we've created CO2.js to simplify the process of estimating energy consumption."

Open-source design is a key feature of all the tools developed by The Green Web Foundation, including CO2.js. "With open-sourcing, the idea is that we share the job of maintaining the tool with a community," says Hannah. "The community members are highly engaged developers committed to improving and maintaining the code of CO2.js. We depend on creative input and feedback to keep on improving the tool. The enthusiasm of the developer group also helps us to increase awareness and adoption of CO2.js."

Support from SIDN Fund

SIDN Fund is an important partner for The Green Web Foundation. "The Fund's financial support has enabled us to improve the quality of the CO2.js dataset, by ensuring that the data is accurate, up-to-date and reliable, for example. We've also launched 2 new versions of the CO2.js package. The latest version, v0.16, includes an updated Sustainable Web Design Model (SWDM), version 4." The SWDM is one of 3 methods that developers can use to estimate digital emissions. Version v0.16 of the package also features Sustainable Web Design Ratings, similar to the labels used to indicate the energy efficiency of household appliances. The ratings enable a developer to set a carbon footprint limit for the website or app they're working on. They can then see how changes to the code influence carbon emissions, and take that into account.

"We're also using the money from SIDN Fund to revise the CO2.js methodology in collaboration with external developers," continues Hannah. "Studying academic papers and applying the findings is extremely time-consuming, so the financial support is very useful in relation to that work." Some of the funding has been allocated to other projects as well, such as the Green Web Dataset: the world's biggest dataset of websites that run on green electricity, which CO2.js uses as a source.

Elise van Schaik, Project Coordinator at SIDN Fund: "The work of The Green Web Foundation helps people to see how the carbon emissions associated with internet use impact the physical world. By providing practical tools, the Foundation enables developers to reduce that impact. It's wonderful that they are aiming for a fossil-fuel-free internet by 2030, because decarbonising is vitally important. By supporting CO2.js, we're making a small contribution to securing that goal. The Green Web Foundation's open-source tools bring a fossil-fuel-free internet a little closer."

Partnerships and real-world deployment

The success of CO2.js depends not only on supportive foundations and developers, but also on people putting the tool to practical use. "A number of big organisations, such as Mozilla, who make the Firefox browser, are using the CO2.js package to visualise their CO2 emissions," Hannah points out. Website Carbon and Ecograder also include CO2.js in their digital tools, enabling users to gauge their websites' climate impact. "We're working closely with Matomo, the organisation behind the open-source, privacy-friendly web analytics tool, to see how CO2.js can be implemented within the Matomo platform," says Hannah. "And, together with The Green Software Foundation, we're looking at ways of reaching a wider audience with CO2.js. We are also developing a hands-on workshop on carbon measurement tools for digital services that will be released in September this year. It's great to see how awareness of digital carbon emissions is growing amongst developers, and how more and more of them are looking to take steps to reduce the footprint of their products. We want to support them in this journey."

A more sustainable and just internet

In the period ahead, the core team behind CO2.js will focus on driving adoption of the tool. "We'll continue working with developers and with key partners who want to implement CO2.js," confirms Hannah. "We've also got plans to introduce new methodologies and data sources. At the moment, for example, CO2.js mainly provides information about the carbon footprint of websites, software and apps. But in the future we envisage the tool incorporating data from other large sources, such as power suppliers. The more relevant data and applications we can add to CO2.js, the more useful the tool will be to users."

Another of The Green Web Foundation's ambitions is to get involved in policy debates. "We realise that most people are going to keep on using the internet all the time," acknowledges Hannah. "And then there's the rise of artificial intelligence, which is relatively energy-intensive. So a regulatory framework is needed to mitigate the environmental and climate impact of our online activities, while also making sure that opportunities aren't missed. We believe that legislation, practical tools and, above all, awareness are needed to achieve a more sustainable and just internet."

Want to sign up for the digital carbon emissions workshop in September? Fill out this form. Or want to know more about CO2.js or contribute to the code? Visit www.thegreenwebfoundation.org/co2-js or get in touch using The Green Web Foundation's contact form.